Collagen sponges or foams have been used as hemostatic agents and more recently as scaffolds for tissue repair in vivo and as research tools in vitro for seeding various cell types to study cell functions in three dimensions. Collagen sponges have a low immunogenicity and consist of a naturally occurring structural protein to which cells can attach, interact with and degrade. In vivo, these sponges are bioabsorbable. However, sponges are usually crosslinked to provide the degree of wet strength and measured resistance to dissolution needed for many of the above-referenced uses. In general, aldehydic crosslinking of collagen sponges or foams reduces or degrades the normal binding sites to which cells and certain molecules secreted by cells attach. Further, collagen sponges, gelatin sponges or polyvinyl alcohol sponges lack biological activity typically present in the extracellular matrix environment of cells. However, because of their deficiencies, crosslinked collagen sponges induce little regeneration in vivo or serve poorly as histiotypic and organotypic models in vitro.
A need exists, therefore, for an improved biopolymer foam that overcomes or minimizes the above-mentioned problems.